The present invention relates generally to excavation apparatus, and more particularly relates to earthworking tooth and adapter assemblies.
Large excavating buckets, loading buckets and the like are typically provided with a series of teeth which are each formed from two primary parts--a relatively large adapter and a relatively small replaceable point. The adapter has a base portion which is connectable to the forward lower lip of the bucket and a nose portion onto which the tooth point is removably secured by a suitable connecting pin. Compared to that of the adapter, the useful life of the point is rather short--the adapter typically lasting through five ore more point replacements until the tremendous earth forces and abrasion to which it is subjected necessitates its replacement.
Because the much larger adapter is considerably more expensive than its smaller replaceable point, it is desirable to replace the point before it has been worn away to the extent that the nose portion of the adapter, disposed within a pocket in the rear end of the tooth, point, is exposed to earth abrasion and also worn away, thereby undesirably loosening the adapter/point fit when a new tooth point is installed on the adapter. On the other hand, it is also desirable not to prematurely replace a tooth point, still having a portion of its useful operating life left, simply to protect the nose portion of its associated adapter from earth abrasion. Such premature tooth point replacement, of course, can also significantly increase the overall expense associated with the particular excavation or loading process.
The proper economic balance is thus struck when the tooth point is replaced just prior to the time at which it wears through to its adapter nose. However, in practice, it is quite difficult to precisely determine this ideal tooth point replacement time, and considerable skill and experience are required to even approximate it because if the adapter nose becomes visible through a side wall portion of its associated tooth point it is usually too late to prevent earth abrasion wear on the adapter nose and the relatively expensive adapter must be prematurely replaced. Because there has heretofore been no reliable method for precisely determining the time at which the adapter nose is about to be exposed through a worn away portion of its tooth point, tooth points of this type are generally removed and replaced well before this tooth wear condition is reached.
Another problem also exists in conventional tooth and adapter assemblies and relates to the preservation of the necessary snug interfit between the adapter nose and the tooth point pocket which receives it. Under normal tooth operating load conditions, a flat top side surface of the tooth pocket bears against and is supported by a corresponding flat top side surface of the adapter nose, and this tooth-supporting force is fairly well distributed over the flat top side surface of the adapter nose.
However, under extreme operating loads the tooth point tends to bend forwardly and downwardly relative to the adapter nose. This undesirably concentrates the adapter nose/tooth engagement along the top front edge of the adapter nose, thereby substantially accelerating nose wear and loosening the critical nose/tooth fit. In turn, this often necessitates premature adapter replacement.
In view of the foregoing, it is accordingly an object of the present invention to provide tooth and adapter assembly apparatus which eliminates or minimizes the above-mentioned and other problems, limitations and disadvantages typically associated with conventional tooth and adapter assemblies.